The present invention relates to an analyzer of organic substances for analyzing a specimen containing organic substances by irradiation of electron beam to the specimen and by performing spectroscopy of fluorescent light emitted from the specimen.
As the conventional methods to analyze organic substances, various methods have been known such as nuclear magnetic resonance method (NMR), infrared spectroscopy, Raman spectroscopy, ultraviolet excitation fluorescence spectroscopy, electron spectroscopy for chemical analysis (ESCA) or X-ray photoelectron spectroscopy (XPS), etc.
As a method to identify and discriminate organic substances using the ultraviolet excitation fluorescence spectroscopy, a method described in "Analyzer for Organic Foreign Substances in Micro-Area Using Micro-Fluorescence Spectroscopy" (Hitachi Review issued in Japan, Vol.73, No.9, September 1991) is known.
However, when the above methods such as nuclear magnetic resonance method (NMR), infrared spectroscopy, Raman spectroscopy, ultraviolet excitation fluorescence spectroscopy, or ESCA (XPS) method are used, measurable range on the specimen is as follows: 100 .mu.m or more in the nuclear magnetic resonance method (NMR), 7 .mu.m or more in the infrared spectroscopy method, 1 .mu.m or more in the ultraviolet excitation fluorescence spectroscopy method, 1 .mu.m or more in the Raman spectroscopy, and 10 .mu.m or more in the ESCA (XPS) method. In none of the above methods, it is possible to analyze organic substance in micro-area, i.e. in size of 1 .mu.m or less.
In the method to discriminate and identify organic substances using ultraviolet excitation fluorescence spectroscopy, as seen in the above literature, fluorescence wavelength range of fluorescent light emitted from the specimen under bombardment of ultraviolet ray is narrow. For example, even when ultraviolet ray with wavelength of 360 nm is bombarded, wavelength of the emitted fluorescent light is limited to that of 450 nm or around. This means that there is limitation in the information obtained for identification of the organic substances.